1. Technical Field
This invention is related to armor, and in particular for helmets or other body protection against blasts and/or small arms fire.
2. Related Technology
Effective armor technologies have been sought for many decades to protect humans, vehicles, and systems against projectile weapons and explosive blasts.
Recent developments by the U.S. Navy in laminate armor are disclosed in U.S. Pat. No. 7,300,893 to Barsoum et al., U.S. Pat. No. 8,746,122 to Roland et al., and U.S. Pat. No. 8,789,454 to Roland et al., each of which is incorporated herein by reference.
U.S. Patent Publication No. 2012/0312150 to Gamache et al., is also incorporated by reference in its entirety. U.S. Pat. No. 6,112,635 to Cohen et al., U.S. Pat. No. 4,179,979 to Cook et al., U.S. Pat. No. 6,912,944 to Lucata et al., U.S. Pat. No. 7,874,239 to Howland et al. describe additional armor-related technologies. Porter, J. R., Dinan, R. J., Hammons, M. I. , and Knox, K. J., “Polymer coatings increase blast resistance of existing and temporary structures”, AMPTI AC Quarterly, Vol. 6, No. 4, pp. 47-52, 2002, describes work at the Air Force Research Laboratory, describes an approach for reducing fragmentation (flying debris) of the structure destroyed by a blast. Tekalur, S. A, Shukla, A., and Shivakumar, K., “Blast resistance of polyurea based layered composite materials”, Composite Structures, Vol. 84, No. 3, pp. 271-81, (2008) discloses test results for layered and sandwiched layers of polyurea and E-glass vinyl ester.
Reference is also made to A. Tasdemirci, I. W. Hall, B. A. Gama and M. Guiden, “Stress wave propagation effects in two- and three-layered composite material”, Journal of Composite Materials, Vol. 38, pp. 995-1009, (2004). Possible mechanisms contributing to the blast and ballistic mitigation of composites are discussed in Xue, Z. and Hutchinson, J. W., “Neck development in metal/elastomer bilayers under dynamic stretchings”, International Journal of Solids and Structures, Vol. 45, No. 3, pp. 3769-78, (2008); in Xue, Z. and Hutchinson, J. W. , “Neck retardation and enhanced energy absorption in metal-elastomer bilayers”, Mechanics of Materials, Vol. 39, pp. 473-487, (2007); and in Malvar, L. J., Crawford, J. E., and Morrill, K. B.; “Use of composites to resist blast”, Journal of Composites for Construction, Vol. 11, No. 6, pp. 601-610, (November/December 2007). Information on the material properties of viscoelastic materials is found in D.I.G. Jones, Handbook of Viscoelastic Vibration Damping, Wiley, 2001, pp. 39-74. A review of mechanical behavior of viscoelastic materials can also be found in R. N. Capps, “Young's moduli of polyurethanes”, J. Acoustic Society of America, V. 73, No. 6, pp. 2000-2005, June 1983.